1) one who has the ability to improvise on a phonograph turntable
2) "one who uses the turntable in the spirit of a musical instrument" (Dj Babu)
3) a musician; a hip-hop disc jockey who in a live/spontaeneous situation can manipulate or restructure an existing phonograph recording (in combination with an audio mixer) to produce or express a new composition that is unrecognizable from its original ingredients.

The story goes that one day in 1979, Theodore was messing around on his brother's turntables, practicing his mixing skills so that he could DJ at parties in the Bronx. As is natural with all teenagers, he had his music up too loud. His mother started banging on the door and yelling at him. In order to listen to her, he put his hand on the record to stop it. He still wanted to keep the groove going, and found himself moving the record back and forth with his hand. It produced a sound he liked, and after his mother left, he spent weeks perfecting this technique, and finally unveiled it at a party during his mix.

Grand Wizzard Theodore is the inventor of the scratch, and the unofficial father of turntablism.